The present invention relates generally to construction or remodeling materials that are identifiable through analysis of a tagging material, and more particularly to such materials that are produced or formulated using settable, water-based slurries.
In the construction of buildings, one of the most common elements is gypsum wallboard, often known as drywall, used in the construction of walls and/or ceilings. One reason for the low cost of wallboard panels is that they are manufactured by a process that is fast and efficient. A slurry, including calcium sulfate hemihydrate and water, is used to form the core, and is continuously deposited on a paper cover sheet moving beneath a mixer. A second paper cover sheet is applied thereover and the resultant assembly is formed into the shape of a panel. Calcium sulfate hemihydrate reacts with a sufficient of the water to convert the hemihydrate into a matrix of interlocking calcium sulfate dihydrate crystals, causing it to set and to become firm. The continuous strip thus formed is conveyed on a belt until the calcined gypsum is set, and the strip is thereafter cut to form boards of desired length, which boards are conveyed through a drying kiln to remove excess moisture.
Walls and ceilings made from gypsum wallboard are conventionally constructed by affixing the panels to studs or joists and filling and coating the joints or seams between adjacent panels with a specially prepared adhesive called a joint compound. This process generally proceeds by placing a taping grade joint compound within the joint formed by the abutted edges of the wallboards and embedding a liquid-permeable tape within the taping compound. When dry (or set), a second coating including a topping grade joint compound is applied over the joint. This may be sanded lightly, then a third coat applied and conventionally finished. Another grade of joint compound is an all-purpose grade that may be used both for embedding the tape and for applying the finish coats.
There are two types of joint compounds that are commonly used. Compounds of the drying type become hard when the water evaporates. Setting type joint compounds become solid upon the absorption of water. Ready-mix formulations of setting type joint compounds often contain retarders to prevent the absorption of water during the shelf life of the product. When it is desirous to use the joint compound, it then becomes necessary to add an accelerator in order to overcome the effects of the retarder.
Drywall joint compounds may be sold either as a dry powder to be mixed with water, or in the form of a ready-mix compound. There are advantages to the ready-mix formula where it is inconvenient to provide or measure the water to be added at the job site. Ready mixed joint compound is typically supplied to the customer in either cardboard cartons or plastic pails in units having volumes of 3.5 to 4.5 gallons (13.25-17.03 L). An example of ready mix joint compound is U.S. Pat. No. 8,822,566, incorporated by reference.
Joint compound is supplied at a viscosity typically higher than what is applied at the jobsite. This allows the contractor to mix in additional water using a power drill and mixing paddle to achieve the desired application viscosity. Additives are used in all types of joint compounds to modify physical and chemical properties of the compound to suit particular purposes.
When customers encounter a problem with a building product of this type, they typically contact a manufacturer of that product to report the defect. If the wallboard or joint compound is applied by a contractor, as is often the case, the homeowner may not know what brand of building material has been used. Even if the homeowner does the work himself, he does not always save the label, container or other product identification. In these cases, it is not unusual for the homeowner to consult with or complain to a manufacturer with whom they are familiar, without being certain that the manufacturer actually made the gypsum-based building material installed in the owner's home.
The manufacturer then spends a significant amount of time investigating the source of the product about which they received a complaint. Often, they find that the product is that of another manufacturer and that the time spent on the investigation was wasted. Manufacturers of such products have a need for a way of quickly and easily determining whether they actually made the joint compound that has been called into question.
Besides gypsum wallboard panels and joint compound, a number of other compositions are used in building construction or remodeling products. These include, but are not limited to, plaster, textures, poured flooring, acoustical products and fiberboard. Any of these compositions are susceptible to questions of identification if a homeowner is unsatisfied with the product performance.
Commonly-assigned U.S. Pat. No. 8,642,346 discloses a tagging material for the above-identified building products. However, in order to determine if the tagging material is present, the sample of building material must be sent to a laboratory for analysis. Such analysis consumes significant time between when the sample is taken and when the results are received, identifying the source of the product being analyzed.